On 02/08/2019 12:10, Mark Brown wrote: > On Fri, Aug 02, 2019 at 09:32:17AM +0100, Thomas Preston wrote: >> On 02/08/2019 00:42, Mark Brown wrote: > >>> Yes, that's definitely doable - we've got some other drivers with >>> similar things like calibration triggers exposed that way. > >> One problem with using a kcontrol as a trigger for the turn-on diagnostic >> is that the diagnostic routine has a "return value". > > You can use a read only control for the readback, or just have it be > triggered by overwriting the readback value. You can cache the result. > Keeping the trigger and result together like that would be better I think, although the routine isn't supposed to run mid way through playback. If we're mid playback the debugfs routine has to turn off AMP_ON, take the device back to a known state, run diagnostics, then restore. Which causes a gap in the audible sound. >> Hm, maybe a better idea is to have the turn on diagnostic only run on >> device probe (as its name suggests!), and print something to dmesg: > >> modprobe tda7802 turn_on_diagnostic=1 > >> tda7802-codec i2c-TDA7802:00: Turn on diagnostic 04 04 04 04 > >> Kirill Marinushkin mentioned this in the first review [0], it just didn't >> really sink in until now! > > You could do that too, yeah. Depends on what this is diagnosing and if > that'd be useful. > The diagnostic status bits describe situations such as: - open load (no speaker connected) - short to GND - short to VCC - etc The intention is to test if all the speakers are connected. So, one might have a self test which runs the diagnostic and verifies it outputs: 00 00 00 00 For example, on my test rig there is only one speaker connected. So it reads: 04 04 00 04 Where the second bit is "open load". So this would fail the test. So in the kcontrol case the test would be something like: amixer sset "AMP1 turn on diagnostic" on amixer sget "AMP1 diagnostic" And the module parameter case: rmmod tda7802 modprobe tda7802 turn_on_diagnostic=1 dmesg | grep "Turn on diagnostic 04 04 04 04" rmmod tda7802 modprobe tda7802 I think the module parameter method is more appropriate for a "Turn-on diagnostic", even though I don't really like grepping dmesg for the result. I'll go ahead and implement that unless anyone has a particular preference for the kcontrol-trigger. Thanks
